Professional Android

Professional Android, 4th Edition shows developers how to leverage the latest features of Android to create robust and compelling mobile apps. This hands-on approach provides in-depth coverage through a series of projects, each introducing a new Android platform feature and highlighting the techniques and best practices that exploit its utmost functionality. The exercises begin simply, and gradually build into advanced Android development. Clear, concise examples show you how to quickly construct real-world mobile applications.

This book is your guide to smart, efficient, effective Android development.

• Learn the best practices that get more out of Android
• Understand the anatomy, lifecycle, and UI metaphor of Android apps
• Design for all mobile platforms, including tablets
• Utilize both the Android framework and Google Play services

About the authors

Reto Meier has been helping Android developers create the best applications possible for their users since the initial Android release in 2007. Reto is an experienced software developer with more than 20 years of experience in application design and development. He has spent 10 years as a Developer Advocate, contributing countless articles, online training, conference talks, and YouTube videos to the developer community.

Ian Lake has approached Android development from multiple angles over the course of the last 8 years. Ian has worked professionally on high profile Android apps as an application developer, provided outreach to the development community as a Developer Advocate, and has contributed to improving the Android framework APIs themselves as part of the Android Framework team.

INTRODUCTION xxxi

CHAPTER 1: HELLO, ANDROID 1

Android Application Development 1

A Little Background 2

The Not-So-Distant Past 3

Living in the Future 3

The Android Ecosystem 3

Pre-installed Android Applications 4

Android SDK Features 5

What Does Android Run On? 6

Why Develop for Mobile? 6

Why Develop for Android? 7

Introducing the Development Framework 7

What Comes in the Box 8

Understanding the Android Software Stack 8

The Android Run Time 10

Android Application Architecture 11

Android Libraries 12

CHAPTER 2: GETTING STARTED 13

Getting Started Developing Android Apps 14

Developing for Android 15

What You Need to Begin 15

Creating Your First Android Application 20

Getting Started Writing Android Apps Using Kotlin 35

Using the Android Support Library Package 36

Developing for Mobile and Embedded Devices 39

Hardware-Imposed Design Considerations 39

Considering the User’s Environment 43

Developing for Android 44

Android Development Tools 48

Android Studio 49

The Android Virtual Device Manager 51

The Android Emulator 51

Android Profiler 52

The Android Debug Bridge 54

APK Analyzer 54

The Lint Tool 55

Monkey, Monkey Runner, and Espresso UI Testing 55

Gradle 56

CHAPTER 3: APPLICATIONS AND ACTIVITIES AND FRAGMENTS, OH MY! 57

Applications, Activities, and Fragments 58

The Components of an Android Application 58

The Android Application Life Cycle, Priority, and Process States 59

Introducing the Android Application Class 61

A Closer Look at Android Activities 61

Creating Activities 62

Using the AppCompatActivity 63

The Activity Life Cycle 64

Responding to Memory Pressure 71

Introducing Fragments 73

Creating New Fragments 73

The Fragment Life Cycle 74

Introducing the Fragment Manager 79

Adding Fragments to Activities 79

Communicating Between Fragments and Activities 85

Fragments without User Interfaces 86

Building an Earthquake Viewer Application 87

CHAPTER 4: DEFINING THE ANDROID MANIFEST AND GRADLE BUILD FILES, AND EXTERNALIZING RESOURCES 95

The Manifest, Build Files, and Resources 96

Introducing the Android Manifest 96

Configuring the Gradle Build 101

Gradle Settings File 101

Project Gradle Build File 102

Module Gradle Build Files 102

Externalizing Resources 107

Creating Resources 108

Using Resources 119

Creating Resources for Different Languages and Hardware 122

Runtime Configuration Changes 126

CHAPTER 5: BUILDING USER INTERFACES 129

Fundamental Android Design 130

Density-Independent Design 130

Android User Interface Fundamentals 131

Assigning User Interfaces to Activities 132

Introducing Layouts 132

Defining Layouts 134

Using Layouts to Create Device-Independent User Interfaces 136

Optimizing Layouts 139

The Android Widget Toolbox 143

Working with Lists and Grids 144

Recycler View and Layout Managers 145

Introducing Adapters 146

Returning to the Earthquake Viewer Application 149

Introducing Data Binding 150

Enabling Data Binding 151

Variables in Data Binding 152

Data Binding for the Earthquake Viewer Application 153

Creating New Views 155

Modifying Existing Views 155

Creating Compound Controls 159

Creating Simple Compound Controls as a Layout 161

Creating Custom Views 162

Using Custom Controls 176

CHAPTER 6: INTENTS AND BROADCAST RECEIVERS 177

Using Intents and Broadcast Receivers 178

Using Intents to Launch Activities 178

Explicitly Starting New Activities 179

Implicit Intents and Late Runtime Binding 179

Determining If an Intent Will Resolve 180

Returning Results from Activities 181

Using Platform-Native Actions to Launch Activities 184

Creating Intent Filters to Receive Implicit Intents 186

Defining an Intent Filter 186

Using Intent Filters for Plug-Ins and Extensibility 194

Introducing Linkify 198

Native Linkify Link Types 198

Creating Custom Link Strings 199

Using the Match Filter 200

Using the Transform Filter 200

Using Intents to Broadcast Events 200

Broadcasting Events with Intents 201

Listening for Intent Broadcasts with Broadcast Receivers 202

Registering Broadcast Receivers in Code 203

Registering Broadcast Receivers in Your Application Manifest 204

Managing Manifest Receivers at Run Time 204

Monitoring Device State Changes through Broadcast Intents 205

Introducing the Local Broadcast Manager 207

Introducing Pending Intents 208

CHAPTER 7: USING INTERNET RESOURCES 211

Connecting to the Internet 211

Connecting, Downloading, and Parsing Internet Resources 212

Why Build a Native Internet App? 212

Connecting to an Internet Resource 213

Performing Network Operations on Background Threads Using View Models, Live Data, and Asynchronous Tasks 214

Parsing XML Using the XML Pull Parser 219

Connecting the Earthquake Viewer to the Internet 220

Parsing JSON Using the JSON Parser 228

Using the Download Manager 233

Downloading Files 233

Customizing Download Manager Notifications 235

Specifying a Download Location 237

Canceling and Removing Downloads 238

Querying the Download Manager 238

Best Practices for Downloading Data without Draining the Battery 241

An Introduction to Internet Services and Cloud Computing 242

CHAPTER 8: FILES, SAVING STATE, AND USER PREFERENCES 245

Saving Files, States, and Preferences 246

Saving and Restoring Activity and Fragment Instance

State Using the Lifecycle Handlers 246

Retaining Instance State with Headless Fragments and View Models 248

View Models and Live Data 248

Headless Fragments 251

Creating and Saving Shared Preferences 252

Retrieving Shared Preferences 253

Introducing On Shared Preference Change Listeners 254

Configuring Auto Backup of Application Files and Shared Preferences 254

Building a Preference UI 256

Using the Preference Support Library 256

Defining a Preference Screen Layout in XML 257

Introducing the Preference Fragment 260

Creating a Settings Activity for the Earthquake Monitor 261

Including Static Files as Resources 267

Working with the Filesystem 267

File-Management Tools 267

Creating Files on Application-Specifi c Internal Storage 268

Creating Files on Application-Specifi c External Storage 268

Accessing Public Directories Using Scoped Directory Access 270

Sharing Files Using File Provider 274

Creating a File Provider 274

Sharing a File Using a File Provider 275

Receiving a File from a File Provider 275

Accessing Files from Other Applications Using the Storage Access Framework 275

Requesting Temporary Access to Files 276

Requesting Persistent Access to Files 277

Requesting Access to Directories 277

Creating New Files 278

Using URI-Based Permissions 278

CHAPTER 9: CREATING AND USING DATABASES 281

Introducing Structured Data Storage in Android 282

Storing Data Using the Room Persistence Library 282

Adding the Room Persistence Library 283

Defining a Room Database 284

Persisting Complex Objects Using Type Convertors 286

Defining Room Database Interactions Using Data Access Objects 288

Performing Room Database Interactions 291

Monitoring Query Result Changes with Live Data 292

Persisting Earthquakes to a Database with Room 294

Working with SQLite Databases 298

Input Validation and SQL Injection 299

Cursors and Content Values 299

Defining a Database Contract 300

Introducing the SQLiteOpenHelper 300

Opening Databases with the SQLite Open Helper 302

Opening and Creating Databases without the SQLite Open Helper 303

Adding, Updating, and Deleting Rows 303

Querying a Database 305

Extracting Values from a Cursor 307

Introducing the Firebase Realtime Database 308

Adding Firebase to Your App 309

Defining a Firebase Database and Defining Access Rules 311

Adding, Modifying, Deleting, and Querying Data from a Firebase Realtime Database 313

CHAPTER 10: CONTENT PROVIDERS AND SEARCH 317

Introducing Content Providers 318

Why Should I Use Content Providers? 318

Creating Content Providers 319

Creating the Content Provider’s Database 320

Registering Content Providers 321

Publishing Your Content Provider’s URI Address 321

Implementing Content Provider Queries 322

Content Provider Transactions 325

Sharing Files Using a Content Provider 327

Adding Permission Requirements to Content Providers 328

Accessing Content Providers with Content Resolvers 330

Querying Content Providers 330

Cancelling Queries 333

Querying for Content Asynchronously with a Cursor Loader 333

Adding, Deleting, and Updating Content 336

Accessing Files Stored in Content Providers 338

Accessing Permission-Restricted Content Providers 339

Using Native Android Content Providers 341

Accessing the Call Log 341

Using the Media Store Content Provider 342

Using the Contacts Content Provider 344

Using the Calendar Content Provider 351

Adding Search to Your Application 354

Defining Your Search Metadata 354

Creating a Search Results Activity 355

Searching a Content Provider 357

Using the Search View Widget 360

Providing Search Suggestions Using a Content Provider 362

CHAPTER 11: WORKING IN THE BACKGROUND 377

Working in the Background 378

Using Background Threads 379

Using Asynchronous Tasks to Run Tasks Asynchronously 379

Manual Thread Creation Using Handler Threads 383

Scheduling Background Jobs 385

Creating a Job Service for the Job Scheduler 386

Scheduling Jobs with the Job Scheduler 388

Scheduling Jobs with the Firebase Job Dispatcher 391

Scheduling Work with the Work Manager 393

An Earthquake-Monitoring Job Service Example 396

Using Notifications to Notify Users 401

Introducing the Notification Manager 401

Working with Notification Channels 402

Creating Notifications 403

Setting a Notification’s Priority 407

Adding Notification Actions 411

Adding Direct Reply Actions 412

Grouping Multiple Notifications 413

Adding Notifications to the Earthquake Monitor 414

Using Firebase Cloud Messaging 417

Triggering Notifications Remotely with Firebase Notifications 418

Receiving Data with Firebase Cloud Messaging 421

Using Alarms 422

Creating, Setting, and Canceling Alarms 423

Setting an Alarm Clock 424

Introducing Services 424

Using Bound Services 425

Creating a Started Service 427

CHAPTER 12: IMPLEMENTING THE ANDROID

DESIGN PHILOSOPHY 433

Introducing the Android Design Philosophy 434

Designing for Every Screen 434

Resolution Independence 435

Supporting and Optimizing for Different Screen Sizes 436

Creating Scalable Graphics Assets 439

Introducing Material Design 445

Thinking in Terms of Paper and Ink 446

Using Color and Keylines as Guides 447

Continuity through Motion 449

Material Design UI Elements 452

The App Bar 452

Applying Material Design to the Earthquake Monitor 455

Using Cards to Display Content 456

Floating Action Buttons 460

CHAPTER 13: IMPLEMENTING A MODERN ANDROID USER EXPERIENCE 463

The Modern Android UI 464

Creating Consistent, Modern User Interfaces

Using AppCompat 464

Creating and Applying Themes Using AppCompat 465

Creating Theme Overlays for Specific Views 466

Adding a Menu and Actions to the App Bar 467

Defining a Menu Resource 467

Adding a Menu to an Activity 468

Adding a Menu to a Fragment 469

Updating Menu Items Dynamically 469

Handling Menu Selections 470

Adding Action Views and Action Providers 470

Going Beyond the Default App Bar 472

Replacing Your App Bar with a Toolbar 472

Advanced Scrolling Techniques for the Toolbar 473

Incorporating Menus without the App Bar 476

Improving the Earthquake Monitor’s App Bar 477

App Navigation Patterns 479

Navigating with Tabs 479

Implementing a Bottom Navigation Bar 482

Using a Navigation Drawer 485

Combining Navigation Patterns 491

Adding Tabs to the Earthquake Monitor 492

Choosing the Right Level of Interruption 496

Initiating a Dialog 497

Let’s Make a Toast 498

Inline Interruptions with Snackbars 499

CHAPTER 14: ADVANCED CUSTOMIZATION OF YOUR USER INTERFACE 501

Expanding the User Experience 502

Supporting Accessibility 502

Supporting Navigation without a Touch Screen 502

Providing a Textual Description of Each View 503

Introducing Android Text-to-Speech 503

Using Speech Recognition 505

Using Speech Recognition for Voice Input 506

Using Speech Recognition for Search 507

Controlling Device Vibration 508

Going Full Screen 508

Working with Property Animations 510

Enhancing Your Views 513

Advanced Canvas Drawing 514

Creating Interactive Controls 530

Composite Drawable Resources 536

Transformative Drawables 536

Layer Drawables 537

State List Drawables 537

Level List Drawables 538

Copy, Paste, and the Clipboard 539

Copying Data to the Clipboard 539

Pasting Clipboard Data 539

CHAPTER 15: LOCATION, CONTEXTUAL AWARENESS,AND MAPPING 541

Adding Location, Maps, and Contextual Awareness to Your

Applications 542

Introducing Google Play Services 542

Adding Google Play Services to Your Application 543

Determining the Availability of Google Play Services 545

Finding Device Location Using Google Location Services 546

Using the Emulator to Test Location-Based Functionality 548

Finding the Last Known Location 549

“Where Am I” Example 551

Requesting Location Change Updates 555

Changing Device Location Settings 560

Updating the Location in the “Where Am I” Example 563

Best Practices When Using Location 566

Setting and Managing Geofences 567

Using the Legacy Platform Location-Based Services 571

Selecting a Location Provider 572

Finding the Last Known Location 574

Requesting Location Change Updates 575

Best Practice for Using the Legacy Location-Based Services 577

Using the Geocoder 580

Reverse Geocoding 581

Forward Geocoding 582

Geocoding Where Am I 583

Creating Map-Based Activities 585

Getting Your Maps API Key 586

Creating a Map-Based Activity 586

Configuring Google Maps 589

Changing the Camera Position with Camera Updates 590

Mapping Where Am I 592

Displaying the Current Location with the My Location Layer 596

Displaying Interactive Map Markers 596

Adding Shapes to Google Maps 599

Adding Image Overlays to Google Maps 602

Adding Markers and Shapes to Where Am I 602

Mapping the Earthquake Example 605

Adding Contextual Awareness 609

Connecting to the Google Play Services API Client and Obtaining API Keys 610

Using Awareness Snapshots 612

Setting and Monitoring Awareness Fences 613

Awareness Best Practices 617

CHAPTER 16: HARDWARE SENSORS 619

Introducing Android Sensors 620

Using the Sensor Manager 620

Understanding the Android Sensors 621

Discovering and Identifying Sensors 623

Determining Sensor Capabilities 625

Wakeup and Non-Wakeup Sensors 627

Monitoring Sensor Results 627

Interpreting Sensor Values 632

Testing Sensors with the Android Virtual Device and Emulator 635

Best Practices for Working with Sensors 637

Monitoring a Device’s Movement and Orientation 637

Determining the Natural Orientation of a Device 638

Introducing Accelerometers 639

Detecting Acceleration Changes 640

Creating a Gravitational Force Meter 642

Determining a Device’s Orientation 645

Creating a Compass and Artificial Horizon 650

Using the Environmental Sensors 654

Using the Barometer Sensor 654

Creating a Weather Station 655

Using Body Sensors 659

User Activity Recognition 662

CHAPTER 17: AUDIO, VIDEO, AND USING THE CAMERA 665

Playing Audio and Video, and Using the Camera 666

Playing Audio and Video 666

Introducing the Media Player 667

Using Media Player for Video Playback 669

Using ExoPlayer for Video Playback 672

Requesting and Managing Audio Focus 674

Pausing Playback When the Output Changes 676

Responding to the Volume Controls 677

Working with a Media Session 678

Using the Media Router and Cast Application Framework 682

Background Audio Playback 686

Building an Audio Playback Service 686

Using a Media Browser to Connect Your Activity to a

Media Browser Service 688

Life Cycle of a Media Browser Service 690

Playing Audio as a Foreground Service 691

Creating Media Style Notifications 693

Using the Media Recorder to Record Audio 695

Using the Camera for Taking Pictures 697

Using Intents to Take Pictures 697

Controlling the Camera Directly 699

Reading and Writing JPEG EXIF Image Details 706

Recording Video 706

Using Intents to Record Video 707

Using the Media Recorder to Record Video 707

Adding Media to the Media Store 710

Inserting Media Using the Media Scanner 710

Inserting Media Manually 711

CHAPTER 18: COMMUNICATING WITH BLUETOOTH,NFC, AND WI-FI PEER-TO-PEER 713

Networking and Peer-to-Peer Communication 713

Transferring Data Using Bluetooth 714

Managing the Local Bluetooth Device Adapter 714

Being Discoverable and Remote Device Discovery 716

Bluetooth Communications 720

Bluetooth Profiles 725

Bluetooth Low Energy 726

Transferring Data Using Wi-Fi Peer-to-Peer 728

Initializing the Wi-Fi Peer-to-Peer Framework 729

Discovering Peers 731

Connecting with Peers 732

Transferring Data between Peers 733

Using Near Field Communication 735

Reading NFC Tags 735

Using the Foreground Dispatch System 736

Using Android Beam 738

Creating Android Beam Messages 739

Assigning the Android Beam Payload 740

Receiving Android Beam Messages 742

CHAPTER 19: INVADING THE HOME SCREEN 743

Customizing the Home Screen 743

Introducing Home Screen Widgets 744

Defining the Widget Layout 745

Defining Your Widget Size and Other Metadata 746

Implementing Your Widget 748

Updating the Widget UI Using the App Widget Manager and Remote Views 749

Forcing Refreshes of Your Widget Data and UI 753

Creating and Using a Widget Configuration Activity 756

Creating an Earthquake Widget 757

Introducing Collection View Widgets 763

Creating Collection View Widget Layouts 764

Updating Collection View Items with a Remote Views Factory 765

Updating Collection View Items with a Remote Views Service 767

Populating Collection View Widgets Using a Remote Views Service 768

Adding Interactivity to the Items within a Collection View Widget 769

Refreshing Your Collection View Widgets 770

Creating an Earthquake Collection View Widget 770

Creating Live Wallpaper 777

Creating a Live Wallpaper Definition Resource 778

Creating a Wallpaper Service Engine 778

Creating a Wallpaper Service 780

Creating App Shortcuts 781

Static Shortcuts 783

Dynamic Shortcuts 784

Tracking App Shortcut Use 785

CHAPTER 20: ADVANCED ANDROID DEVELOPMENT 787

Advanced Android 788

Paranoid Android 788

Linux Kernel Security 788

Re-introducing Permissions 789

Storing Keys in the Android Keystore 792

Using the Fingerprint Sensor 792

Dealing with Different Hardware and Software Availability 793

Specifying Required Hardware 794

Confirming Hardware Availability 795

Building Backward-Compatible Applications 795

Optimizing UI Performance with Strict Mode 797

Telephony and SMS 798

Telephony 799

Sending and Receiving SMS Messages 806

CHAPTER 21: RELEASING, DISTRIBUTING, AND MONITORING APPLICATIONS 825

Preparing for Release 826

Preparing Release Support Material 826

Preparing Your Code for a Release Build 827

Updating Application Metadata in Your Application Manifest 828

Reviewing Application Installation Restrictions 828

Application Versioning 830

Signing Production Builds of Your Application 830

Creating a Keystore and Signing Key with Android Studio 832

Obtaining API Keys Based on Your Private Release Key 833

Building and Signing a Production Release 834

Distributing Your Application on the Google Play Store 835

Introducing the Google Play Store 835

Getting Started with the Google Play Store 836

Creating an Application on the Google Play Store 837

Publishing Your Application 845

Monitoring Your Application in Production 848

An Introduction to Monetizing Applications 853

Application Marketing, Promotion, and Distribution Strategies 854

Application Launch Strategies 854

Internationalization 855

Using Firebase to Monitor Your Application 856

Adding Firebase to Your Application 856

Using Firebase Analytics 857

Firebase Performance Monitoring 860

INDEX 863

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